Wet Tree Semi-Submersible With SCRs for 4,000 ft Water Depth in the Gulf of Mexico

2011 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao ◽  
Sherry Xiang
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Cost Effective ◽  
Integrated System ◽  
Fatigue Performance ◽  
Strength Performance ◽  
Field Development ◽  
Vessel Motion ◽  
Optimum Solution ◽  
Mitigation Methods

This paper presents a design of a deep draft wet tree semi-submersible with steel catenary risers (SCRs) for 4,000 ft water depth in the Gulf of Mexico (GoM). The integrated system of hull, mooring, and SCRs is discussed. The design challenges of SCRs are highlighted and results of SCR strength and fatigue performance are presented. A comparison study on strength performance of various types of risers under the GoM environment criteria is performed. The assessment of extreme strength responses from various riser and hull configurations provide guidelines for the best hull selection. Sour service requirement creates challenges in the fatigue design of the production riser system at such water depth. Integrated mooring and riser design provides an optimum solution. It’s found that the majority of riser fatigue damage at touch down zone is generated by wave loading & resultant vessel motion and vortex induced vessel motion (VIM). Several fatigue mitigation methods are suggested to improve the riser fatigue performance, such as planned vessel repositioning. The conclusion of this study is that deep draft wet tree semi-submersible with SCRs can be a cost effective solution for field development at 4,000 ft water depth in the Gulf of Mexico.

Design of Steel Lazy Wave Riser for External Turret Moored FPSO

2019 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Fatigue Performance ◽  
Effective Solution ◽  
Field Development ◽  
Riser Design ◽  
Preferred Solutions ◽  
Design Challenges ◽  
Selection Of

Abstract The external turret moored Floating Production Storage and Offloading system (FPSO) is one of the preferred solutions for deepwater fields in mild to moderate environments and far away from existing pipeline infrastructures. This paper presents a design of steel lazy wave riser (SLWR) system for an external turret moored FPSO in the water depth of 1,500 meter. The design challenges and feasibility are discussed. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser extreme and fatigue performance target, as well as external turret layout. The study includes the standardized FPSO, the selection of turret configuration, and riser design. The titanium taper stress joints and the interaction with turret structure are also studied. The study provides an optimal solution of the integrated turret, mooring and riser system. It concludes that external turret FPSO with SLWRs can be a feasible and cost effective solution for field development in mild to moderate environments.

Steel Lazy Wave Riser Design for Semi-Submersible in Harsh Environment

2014 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Harsh Environment ◽  
Depth Range ◽  
Strength Performance ◽  
Field Development ◽  
Steel Catenary Risers ◽  
Riser Design ◽  
Design Guidance

Deep draft production semi-submersible with steel lazy wave risers (SLWRs) has been studied for the 2,625ft water depth in harsh environment. The design challenges and feasibility of steel catenary risers (SCRs) for semi-submersible at relatively shallow water and harsh environment are discussed. The benefits of using SLWRs to improve riser strength and fatigue performance are presented. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser performance target. A comparison study on fatigue and strength performance of various riser configurations is performed. The assessment provides design guidance for the optimal solution of the integrated hull, mooring and riser system. It concludes that deep draft production semi-submersible with SLWRs can be a feasible and cost effective solution for field development at water depth range from 2,297ft to 3,281ft in harsh environment.

Design of Steel Lazy Wave Riser for Disconnectable FPSO in the Gulf of Mexico

2013 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Gulf Of Mexico ◽  
Water Injection ◽  
Integrated Design ◽  
Cost Effective ◽  
Performance Criteria ◽  
Harsh Environment ◽  
Effective Solution ◽  
Field Development ◽  
Integrated Design Approach ◽  
Preferred Solutions

The disconnectable Floating Production Storage and Offloading system (FPSO) is one of the preferred solutions for the deepwater field in the harsh environment and far away from existing pipeline infrastructures. This paper presents a design of steel lazy wave riser (SLWR) system for an internal turret moored disconnectable FPSO in the Gulf of Mexico. The integrated systems of FPSO, disconnectable buoy, riser, and mooring are discussed while focusing on the design challenges of SLWR system. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced based on buoy payload and riser performance criteria. The study includes the strength and fatigue analysis of production, gas export and water injection risers for the connected, disconnecting, and disconnected conditions. The sensitivity of buoy disconnecting due to vessel offset is also presented. It concludes that SLWR with disconnectable FPSO is a feasible and cost effective solution for deepwater field development in the Gulf of Mexico. The study demonstrates the importance of an integrated design approach, and provides guidance for configuring and design of future disconnectable systems with SLWRs.

The State of Dry-Tree Semi-Submersible Platforms for Deepwater Gulf of Mexico

2014 ◽  
Author(s):  
Ming-Yao Lee ◽  
Jack Zeng ◽  
Philip Poll
Keyword(s):  
Gulf Of Mexico ◽  
Technology Acceptance ◽  
Model Test ◽  
Water Depth ◽  
Technology Development ◽  
Cost Effective ◽  
Test Results ◽  
Scaled Model ◽  
Size Limits ◽  
Long Stroke

The use of semi-submersible platforms has become increasingly popular due to its ability to carry large topsides and the possibility for quayside integration. With recent exploration successes in ultra-deepwater fields of the Gulf of Mexico, major oil and engineering companies are keen to look for a safe, reliable and cost-effective dry-tree option to maximize the value of deepwater field developments. Dry-tree semi-submersible (DTS) emerges as such an option to overcome the water depth and size limits imposed by TLP and Spar, respectively, and enables the platform to carry a large well array and payloads in ultra-deep water. This paper presents the offshore industry’s multi-year efforts to mature two promising semi-submersible platform concepts that can accommodate long-stroke dry-tree risers and have large drilling and production capabilities. Results of technology development and qualification will be highlighted with details on hull performance and hull/riser interfaces. Key structural, mooring and riser analyses and scaled model test results including the long-stroke riser tensioning system will be presented. Remaining challenges that need to be overcome to advance the DTS concepts from “technology acceptance” to “project readiness” will also be discussed.

scholarly journals COBRA Riser Concept for Ultra Deepwater Condition

2013 ◽  
Author(s):  
Tomy Nurwanto ◽  
Daniel Karunakaran ◽  
Ricardo Franciss
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Sudden Change ◽  
Cost Effective ◽  
Mooring Lines ◽  
Strength Performance ◽  
Design Performance ◽  
Cluster Region ◽  
Sea Bed ◽  
Flexible Jumper

Offshore ultra deepwater field is being promising as the future of oil and gas reserves. However, the development of ultra deepwater field posed many challenges, in particular, on the selection of the riser concept. Long suspended length of riser will significantly increase the vessel payload. High external hydrostatic pressure on the riser will increase the probability of collapse failure. Large dynamic motions of the vessel and large vessel offset yields potential buckling issues at the touch-down-point (TDP). In addition, potential fatigue problems due to vessel motions and soil-riser interactions also present at TDP area. Large current speed in deepwater field might also lead to vortex induced vibration (VIV) which eventually will contribute to significant fatigue damage for particular riser sections. By looking into these challenges, it is very important to select the most appropriate riser concept for the ultra deepwater field. Catenary Offset Buoyant Riser Assembly (COBRA) as newly developed hybrid riser concept offers a solution to overcome the challenges in ultra deepwater field. In general, COBRA consists of a catenary riser section with a long-slender sub-surface buoyancy module on top which is tethered down to sea bed via two mooring lines. The catenary section from top of the sub-surface buoy is connected to the floater by a flexible jumper. This flexible jumper can effectively absorb the floater motions, which give significant improvements for both strength and fatigue performance on the overall system. As a hybrid riser concept, this concept offers cost effective solution by avoiding all the expensive bottom assemblies that normally needed for a hybrid riser concept. This paper focuses on COBRA riser concept specifically for Santos Basin Central Cluster region at 2200 m water depth. It is observed that there is common sudden change phenomenon on the current direction in Santos Basin area. The effect of bidirectional current is analyzed, and the comparison with unidirectional current is discussed thoroughly. The analyses are focused on the global strength design performance under extreme environmental load and global fatigue design performance of the riser due to wave induced and VIV induced. The results clearly indicate that COBRA riser concept has a robust design and it is feasible for 2200 m water depth, in particular for Santos Basin Cluster Region area. It is also shows that COBRA riser has sufficient strength performance even for extreme bidirectional current.

scholarly journals ANN-Based Decision Making in Station Keeping for Geotechnical Drilling Vessel

2021 ◽  
Vol 9 (6) ◽  
pp. 596
Author(s):  
Murugan Ramasamy ◽  
Mohammed Abdul Hannan ◽  
Yaseen Adnan Ahmed ◽  
Arun Kr Dev
Keyword(s):  
Decision Making ◽  
Water Depth ◽  
Business Models ◽  
Cost Benefit ◽  
Cost Effective ◽  
Station Keeping ◽  
Operational Information ◽  
Effective Option ◽  
The Cost ◽  
Cost Factors

Offshore vessels (OVs) often require precise station-keeping and some vessels, for example, vessels involved in geotechnical drilling, generally use Spread Mooring (SM) or Dynamic Positioning (DP) systems. Most of these vessels are equipped with both systems to cover all ranges of water depths. However, determining which system to use for a particular operational scenario depends on many factors and requires significant balancing in terms of cost-benefit. Therefore, this research aims to develop a platform that will determine the cost factors for both the SM and DP station-keeping systems. Operational information and cost data are collected for several field operations, and Artificial Neural Networks (ANN) are trained using those data samples. After that, the trained ANN is used to predict the components of cost for any given environmental situation, fieldwork duration and water depth. Later, the total cost is investigated against water depth for both DP and SM systems to determine the most cost-effective option. The results are validated using two operational scenarios for a specific geotechnical vessel. This decision-making algorithm can be further developed by adding up more operational data for various vessels and can be applied in the development of sustainable decision-making business models for OVs operators.

Development of efficiency increase methods for water injection

2020 ◽  
pp. 57-60
Author(s):  
K.I. Mustafaev ◽  
◽  
◽  
Keyword(s):  
Water Injection ◽  
Cost Effective ◽  
Current Interest ◽  
Residual Oil ◽  
Production Well ◽  
Field Development ◽  
Oil Reserves ◽  
Production Wells ◽  
Efficiency Increase

The production of residual oil reserves in the fields being in a long-term exploitation is of current interest. The extraction of residual oil in such fields was cost-effective and simple technological process and is always hot topic for researchers. Oil wells become flooded in the course of time. The appearance of water shows in production wells in the field development and operation is basically negative occurrence and requires severe control. Namely for this reason, the studies were oriented, foremost, to the prevention of water shows in production well and the elimination of its complications as well. The paper discusses the ways of reflux efficiency increase during long-term exploitation and at the final stages of development to prevent the irrigation and water use in production wells.

Greater Plutonio Riser Tower Installation: Studies and Lessons Learnt

2009 ◽  
Author(s):  
Charles-Alexandre Zimmermann ◽  
Guilhem Layrisse ◽  
Daniel de la Cruz ◽  
Jeremy Gordonnat
Keyword(s):  
Water Depth ◽  
Bending Moment ◽  
Lessons Learned ◽  
Field Development ◽  
System A ◽  
Analysis Methodology ◽  
Lessons Learnt ◽  
Future Improvement ◽  
Tower System

The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a Hybrid Riser Tower comprising 11 risers bundled around a central structural tubular (Core Pipe), tensioned by a steel Buoyancy Tank at its top and maintained by an anchor base at its bottom. The Riser Tower is fabricated onshore and then towed to the field for final installation in deepwater near the FPSO. Once the Riser Tower installation is completed the risers are connected to the FPSO by means of flexible jumpers and to the flowlines by means of rigid spools. All fabrication and installation work has been performed by Acergy. This paper presents the studies performed to cover all the steps of the installation phase: build-up of the Orcaflex model, miscellaneous studies to determine model and analyses parameters, towing analysis, upending analysis, Buoyancy Tank ballasting and deballasting analyses, and contingency analyses. This paper is mainly focused on the Riser Tower installation but also covers the installation of the Riser Tower anchor and of the flexible jumpers in order to give a complete overview of the operations related to the Riser Tower system. A comparison between computed data and data measured during operations is also presented to support the overall installation analysis methodology. Lessons learned are provided for future improvement of Riser Tower installation covering main challenges such as Riser Tower modeling, weight/buoyancy repartition along the Riser Tower, Buoyancy Tank ballasting adjustment in Lobito bay, fatigue issues during surface and subsurface tow, bending moment issues during upending, etc.

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